1 a) (a+b)²=a²+2ab+b²
б) (a-b)²=a²-2ab+b²
в) (a²-b²)=(a-b)(a+b)
2 a) (a-3)(a+3)-(2-a)²=
=a²-9-(4-4a+a²)=4a-13
б) (2a+3b)(3b-2a)-(a-b)(b+a)
=9b²-4a²-(a²-b²)=
=10b²-5a²
в) (x-2)(x+2)(x-3)(x+3)=
=(x²-4)(x²-9)=x⁴-9x²-4x²+36=x⁴-13x²+36
г)(5-а)²-(а+1)²+5(2-а)(2+а)=
=25-10а+а²-(а²+2а+1)+5
(4-а²)=25-10а+а²-а²-2а-1
+20-5а²=44-12а-5а²